Welcome Guest! If you are already a member of the BMW MOA, please log in to the forum in the upper right hand corner of this page. Check "Remember Me?" if you wish to stay logged in.

We hope you enjoy the excellent technical knowledge, event information and discussions that the BMWMOA forum provides.
Why not take the time to join the club, so you can enjoy posting on
the forum, the club magazine, and all of the discounts and benefits the BMWMOA offers?Want to read the MOA monthly magazine for free? Take a 3-month test ride of the magazine; check here for details.

If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You will need to join the MOA before you can post: click this register link to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

NOTE. Some content will be hidden from you. If you want to view all content, you must register for the forum if you are not a member, or if a member, you must be logged in.

R90S carb parts/advice

I've done a bunch of Bing's and enjoy fussing with them to make them purr. I am working on getting a '76 R90S that has low miles and has not really been ridden much for since 1999. Tires are DOT dated 1999 and look like new (although I would never run on them more than around town during tuning etc.) he says he has only run it maybe 1,000 miles, I would agree with that after looking at the tires etc. Bike starts up but needs to run at 2,800 to about 3,300, just runs kind of choppy, not smooth until the higher RPM then she smoothes out nicely, not happy at an idle. While I can spell Delloto I can't yet pronounce it....where should I look for a carb rebuild kit and tuning advice for the 90S series? Cool carbs btw. I am assuming the rubber O rings got to have ended their life some time ago, any other parts that should be replaced while still staying in the stock mode? My plan at this point if I buy it will to freshen it up and enjoy it on short rides as I have a slash 7 that loves me best when away from home. She and I have something.
Kurt

When I rebuilt the Dells on my old R90S, I got my parts from Rusty at Max BMW. They had a rebuild kit.

The carbs are not bad to rebuild, two weak areas though. The nut on the float bowl bottom is easily stripped and hard to find a replacement. It has cut-outs in the threaded area to allow gas to flow to the main jet. The accelerator pump works on a plastic lever riding in cut-out of the throttle slide, it can be broken easily. The lever pushes against the accelerator pump. Do not mess with the adjustment on the accelerator pump, just replace any parts needed, such as the rubber pieces. Once rebuilt, adjusting them is the same as any carb, and they hold their synch pretty well.

Rebuilding Dellortos

Kurt,
I rebuilt the Dellorto's on my 1975 R90S with rebuild kits from Bevel Heaven in California. Steve at Bevel Heaven also carries beautiful billet "bolts" for the bottom of the float bowls. I also replaced the floats as the old floats don't do well with gas that has ethanol. A couple of tips I'd pass along are: 1) to find a small ultrasonic cleaner and clean the carb bodies for hours to clean out the tiny inner passages, and 2) make sure you set the float height correctly for the Dellortos you have by bending the tab that contacts the needle-seat assembly. 3) make sure you notice which of the three indents the long needle is set to as you open up the carbs.

dells. . .

You can also BOIL the carb bodies in distilled (or reverse osmosis) water for at least 30 minutes to clean all the passages. Don't do this inside, unless you're single, as the aroma might not please everyone -- only Airhead fanciers. I bought a big pan at Goodwill specifically for the purpose, and use my outdoor (electric) grill as a heat source. Learned this trick from Randakk, a Goldwing/Honda guru.

Float height: I just pass this along, because I found it SO strange. When I disassembled the dells, I found the float-height adjustment to be WAY out, and wondered about it. After a cleaning, I VERY PRECISELY re-set floats to factory spec, and NO GAS would flow, at all (!) I ended up bending the tabs back to approximately where they were -- just took a "stab" at it so the bowls would fill, and was good to go. NO LEAKS from the carbs, and the bike goes down the road real good.

I guess I should add that these dells are mounted to a 78 R100RS Motorsport, so YRMV, due to a possible difference in mounting angle, etc.

Looks like there are a couple of experts on these carbs. However, I have not seen one correct spelling......so, I can once again be a smart aleck:Dell'Orto

Having worked on both R90Ses and R100Ses, the best thing one can do to a R90S in my opinion, is, to change the pumpers over to Bings. The bike will not suffer, as far as street performance is concerned.